High pressure fluid delivery systems have been used for many applications. Details of such systems are illustrated in U.S. Pat. Nos. 3,765,607 and 4,349,154, both assigned to the assignee of the present invention. Such systems typically use water for cleaning fluid and include a high pressure pump and a hand-held nozzle for directing a stream of fluid at an object to be cleaned. Most such systems also include a valve arrangement, usually in the hand-held nozzle assembly, by which the operator can stop and start the flow of high pressure fluid through the nozzle. Due to the fact that the pressures used in such systems often exceed 10,000 psi, the construction of valves that will operate safely is much more difficult than it would at first seem. The valves often require considerable force to operate and result in operator fatigue. The high pressure flow from the nozzle assembly is usually stopped by simply switching the flow to a large opening coupled to ambient pressure. It is sometimes desirable for the dump outlet to be located remotely from the nozzle while the valve is controlled from the nozzle location.
Further, because of the high pressures used in these valves, the parts erode very quickly. In addition, there is a limit to the pressure or flow that can be handled by a hand-controlled valve simply because of the forces involved. Also, in the prior art devices, a shut-off pin and its seal have to be made very large and rugged because of erosion and thus are expensive to manufacture and maintain. Further, in the prior art, the only way to operate the high pressure valve at a remote distance is with a solenoid. It would be desirable to be able to provide a remote controlled valve coupled through a small hose to a trigger housing.
The present invention overcomes the disadvantages of the prior art by providing an improved power assisted dump valve which has a unitary housing or valve body with a fluid passageway extending through the valve body and having a low pressure fluid source coupled to one end as the input and a high pressure fluid nozzle assembly coupled to the other end as the output. A valve chamber extends into the unitary valve body and is sealably closed at one end with a fluid pressure dump assembly. The assembly has a channel therein for dumping fluid in the valve chamber to the atmosphere. A piston is slidably carried in the valve chamber. The piston has a first portion with a first diameter for sealably separating the chamber into first and second sections and a second portion with a second smaller diameter extending into the second chamber section for sealably mating with the channel in the dump assembly to prevent fluid flow to the atmosphere. A resilient spring member is interposed between the piston and the first chamber section to urge the piston into sealing relationship with the channel in the dump assembly. The combined relationship of the spring and the fluid pressure on the piston causes a snap action when the piston closes the dump channel. Because of this snap action and the high sealing force, even if there are slight imperfections in the channel in the dump assembly, the pressure will deform the slight imperfections and make a good seal. A control valve is coupled to the first chamber section for selectively closing and venting the first chamber section such that when the control valve is in the closed position, the dump assembly channel is sealed with the snapping action of the piston and fluid is forced at a high pressure out the high pressure nozzle and, when the control valve is in the vent position, the dump assembly channel is open and the fluid is dumped to ambient pressure so as to remove the high pressure at the output of the high pressure nozzle.
The control valve is associated with a plate rigidly connected to the unitary valve body. A second fluid passageway is formed in the unitary valve body coupling the first chamber section to the outside of the unitary valve body. A control orifice in the plate is in sealed fluid flow alignment with the second fluid passageway in the unitary valve body. A shut-off pin is sealably and slidably mounted in the plate for movement between first and second positions to selectively open and close the control orifice thereby venting and closing the first chamber section. A third passageway in the plate assembly couples the control orifice to the atmosphere such that when the shut-off pin opens the control orifice, the first chamber portion in the unitary valve is vented to atmosphere so as to enable the fluid pressure to move the piston to open the channel in the fluid pressure dump assembly and remove the high pressure from the high pressure nozzle assembly. When the shut-off pin closes the control orifice, the first chamber portion in the unitary valve is pressurized through a second orifice in the piston to cause the piston to close the dump assembly in conjunction with the spring with a snapping action.
Because the shut-off pin is formed in a separate plate that is attached to the unitary valve body, the components in the plate including the shut-off pin and associated components can be made smaller and less expensive even if they are quickly eroded because they can be easily and economically replaced.
As an additional safety feature, an additional control valve is placed in parallel with the first control valve such that when the additional control valve is open or vented, the high pressure cannot be created by operating the first control valve.
Thus, it is an object of the present invention to provide an improved power assisted dump valve with no limit to the pressure or flow that can be handled by the improved hand-controlled dump valve.
It is also an object of the present invention to provide a control valve with a spring urging a piston to seal the dump valve channel such that an incoming pressure offsets the spring pressure and balances the piston in the valve body to keep the dump valve channel open. When a valve controller is actuated so as to cause the full pressure to assist the spring, the valve closes the dump channel with a snapping action thus providing a high sealing force so that even if there are slight imperfections in the dump channel sealing area the pressure will deform the imperfections and make a good seal.
It is still another object of the present invention to provide a remote-controlled device with the improved dump valve so that it can be operated from a distance.
It is yet another object of the present invention to provide an additional control valve in parallel with the first control valve such that when the additional control valve is in the open or vent position, the high pressure that cannot be created by operating the first control valve thus providing a safety feature.